720240421 has 4 divisors (see below), whose sum is σ = 728333100. Its totient is φ = 712147744.

The previous prime is 720240403. The next prime is 720240457. The reversal of 720240421 is 124042027.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 488896321 + 231344100 = 22111^2 + 15210^2 .

It is a cyclic number.

It is not a de Polignac number, because 720240421 - 2¹³ = 720232229 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 720240392 and 720240401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720240461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4046206 + ... + 4046383.

It is an arithmetic number, because the mean of its divisors is an integer number (182083275).

Almost surely, 2^720240421 is an apocalyptic number.

It is an amenable number.

720240421 is a deficient number, since it is larger than the sum of its proper divisors (8092679).

720240421 is an equidigital number, since it uses as much as digits as its factorization.

720240421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8092678.

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 720240421 is about 26837.2953369001. The cubic root of 720240421 is about 896.3806996734.

Adding to 720240421 its reverse (124042027), we get a palindrome (844282448).

The spelling of 720240421 in words is "seven hundred twenty million, two hundred forty thousand, four hundred twenty-one".